In ArF immersion lithography and extreme ultraviolet (EUV) lithography, finer widths of resist lines have been desired. When fine resist patterns are formed, the area at which the resist patterns are in contact with a base substrate is small to make the aspect ratio (resist height/resist line width) high, which raises concerns for the tendency of the resist patterns to collapse. Because of this, a resist underlayer film (an anti-reflective coating) in contact with a resist is required to be highly adhesive to the resist so that resist patterns do not collapse.
Patent Document 1 describes that, in order to make a resist underlayer film highly adhesive to a resist, the use of a lactone structure as a constituent of a composition for forming a resist underlayer film enhances adhesion of the resultant resist underlayer film to resist patterns. In other words, the use of a structure having a polar moiety such as a lactone structure as a constituent of a composition for forming a resist underlayer film is expected to enhance adhesion to resist patterns and even prevent fine resist patterns from collapsing.
However, in the process of lithography such as ArF immersion lithography and extreme ultraviolet (EUV) lithography in which finer resist patterns are required to be formed, such use of a lactone structure as a constituent of a composition for forming a resist underlayer film is not enough for preventing resist patterns from collapsing.